Understanding NASA Low Outgassing Standards
NASA developed a method to screen low outgassing materials for use in space applications. The standard test, defined by ASTM E595, measures the volatile content of materials placed in a heated vacuum chamber. This method is widely used to evaluate adhesives and other polymers for aerospace and satellite systems.
The test results are highly dependent on how the adhesive is cured. Once cured according to manufacturer-recommended schedules, samples are preconditioned at 50% relative humidity for 24 hours and then weighed. They are then placed in a vacuum chamber at 125°C under 5×10⁻⁵ torr. Over a 24-hour period, volatiles that outgas condense onto a collector plate cooled to 25°C. The sample and collected material are weighed to determine total mass loss (TML) and the amount of collected volatile condensable materials (CVCM).
Testing Process for Outgassing Compliance
Materials are evaluated based on two key metrics:
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Total Mass Loss (TML): Must be less than 1.00%
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Collected Volatile Condensable Materials (CVCM): Must be less than 0.10%
Both thresholds must be met for a material to be considered compliant with NASA’s low outgassing requirements. These criteria are essential in environments such as spacecraft or satellites, where outgassing can affect sensitive electronics and optics.
Epoxyset EB-135: NASA-Qualified Adhesive
Most recently, Epoxyset’s EB-135 adhesive and potting compound was tested under three different cure schedules and passed all requirements. EB-135 is a high-performance, unfilled epoxy with excellent optical properties and chemical resistance. It is designed to cure at room temperature and performs well in vacuum and high-temperature conditions.
EB-135 Outgassing Test Results
Cure: 24 hours at 25°C
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TML – 0.83%
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CVCM – 0.08%
Cure: 3 hours at 65°C
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TML – 0.59%
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CVCM – 0.06%
Cure: 2 hours at 80°C
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TML – 0.60%
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CVCM – 0.07%
